What nominal size should the fittings for fire pump and jockey pump pressure sensing lines be?

The appropriate nominal size for the fittings for fire pump and jockey pump pressure sensing lines is 1/2". This size is commonly used for sensor connections because it provides an adequate flow rate while maintaining the necessary pressure response for accurate readings.

In fire protection systems, pressure sensing lines must be adequately sized to ensure that they can relay pressure changes effectively to the monitoring equipment. A smaller diameter, such as 1/2", is suitable for these applications because it helps mitigate the risk of clogging and minimizes the volume of fluid in the sensing line, allowing for quicker response times to pressure changes.

Larger sizes, such as 3/4", 1", or 2", would not be ideal because they could introduce excessive fluid volume, leading to a delayed response in sensing the pressure change. The increased size could also complicate installation and maintenance, as well as contribute to potential water hammer issues in the system.

Overall, the selection of 1/2" for fire pump and jockey pump pressure sensing lines aligns with established practices in fire protection system design, ensuring reliability and efficiency in pressure monitoring.